Power transmission clutch



Nov. 10, 1936. H. M. ROCKWELL 2,060,692

POWER TRANSMISSION CLU'I'QH Original Filed June 11, 1931 4 Sheets-Sheet 1 INVEN TOR.

ATTORNEY.

Nov. 10, 1936. M, ROCKWELL 2,060,692

POWER TRANSMISSION CLUTCH Original Filed June 11, 1931 4 Sheets-Sheet 2 A TTORNE Y.

Nov. 10, 1936. H. M. ROCKWELL 2,060,692

POWER TRANSMISS ION CLUTCH Original Filed June 11, 1951 4 Sheets-Sheet 3 IN VEN TOR.

A TTORNEY.

Nov. 10, 1936. H. M. ROCKWELL 2,060,692

POWER TRANSMISSION CLUTCH Original Filed June 11, 1931 4 Sheets-Sheet 4 INVENTOR.

A TTORNE Y.

Patented Nov. 10, 1936 PATENT OFFICE 2,060,692 POWER TRANSMISSION CLUTCH Hugh M. Rockwell, Freeport, N. Y.

Refiled for application Serial No. 543,529, June 11, 1931. This application December 20, 1.932,

Serial No. 648,116

19 Claims.

The present invention relates to clutches for power transmission purposes, and refers more particularly to novel clutches and clutch actuating means which are especially well suited for use as automotive equipment.

In my earlier application, Serial No. 264,765,

I filed March 26, 1928, I have disclosed a novel power transmission clutch and hydraulic control means therefor, and the present invention is, in part, a carrying forward of the same broad inventive concept, with substantial additions, improvements, and refinements. The present invention formed the subject matter of my 'application Serial No. 543,529flled June 11, 1931, of which this application is a refiling.

One of the objects of this invention is to provide a clutch with novel fluid pressure actuating means of such a character that the shaft will be free from any objectionable end thrusts as the clutch is engaged and released, and there will be no relatively rotating parts required to operate the clutch.

Another object of this invention is to provide an efiicient clutch unit characterized by compactness of arrangement and simplicity of construction.

Another object of the invention is to provide such a clutch in which all the parts are well balanced with reference to the axis of rotation, and well fitted whereby to eliminate whipping, chattering, and the like.

A further object is to provide a clutch wherein all actuating parts, including springs, are entirely inclosed in rotating annular members, and wherein novel and simplified means are employed to control the alternate engagement and release of the clutch.

Another object of the invention is to provide in a clutch, means for gradually engaging the cooperating members in their final engaging movement, whereby to permit smoother operation and eliminate grabbing.

Another object of the invention is to provide such a clutch wherein the actuating forces are distributed more advantageously than in prior art devices.

Another object is to provide a clutch or clutch system wherein wear of the parts is taken up automatically and in such a manner as always to maintain a definite relative movement of the operating pedal or equivalent actuating means.

Still another object is to provide a novel and simplified means for controlling a clutch hydraulically.

Another object of the inv ntion is to provide an improved master cylinder unit for motor vehicles having either hydraulic brakes, hydraulic clutch, or both.

Another object is to provide a clutch which can readily be disposed within an engine flywheel, 5 with the clutch-actuating means disposed at the driving side whereby substantially to reduce the total length of an automotive power plant.

The foregoing and other objects, features, and advantages of the invention will be fully under- 10 stood from the following description in connection with the accompanying drawings, wherein, the invention has been shown only by way of illustration, and wherein Figure 1 is a vertical, transverse, sectional view 16 through one form of clutch embodying the invention; Fig. 2 is an end view thereof; partly broken away and partly in section;

Fig. 3 is a top plan view of an automobile chas- 20 sis equipped with the clutch and control means of this invention;

Fig. 4 is a top plan view of the improved clutch and brake control unit per se;

Fig. 5 is a vertical, transverse, sectional view on line 5-5 of Fig. 4, and showing the clutch control cylinder;

' Fig. 6 is a vertical transverse, sectional view on line 6 6 of Fig. 4, and showing the brake control cylinder; and

Fig. 7 is a vertical, transverse, sectional view through another embodiment of the invention.

In Figs. 1 and 2, the novel clutch III has been shown in conjunction with afiywheel such as is commonly used in automotive engines, but the in- 35 vention is not necessarily limited to such ah arrangement. This illustrated embodiment provides a disengageable driving connection between a driving shaft I I and a driven shaft l2, the driving shaft II in this instance being an engine crankshaft journalled in a bearing I4, while the driven shaft I2 is part of the usual speed change transmission. These shafts are, of course, in axial alinement and may be of any ordinary, desired, or conventional form. For example, the 45 shaft l2 extends through the end wall [5 of the transmission case, and is journalled intermediate its ends as at I 6 in an anti-friction bearing H. The inner end of the shaft is provided with a gear I8 and adapted for connection to a jack shaft or the like, not shown, while the outer end is reduced in diameter and piloted in the inner race of a ball bearing l9 which is fitted into the center of a fiy wheel 20. g

The end of the shaft I I is formed with a flange 2| to which the flywheel 20 is secured as by a series of bolts 23 and nuts 24. The peripheral portion of the flywheel is of increased thickness,

as usual, and provided with a ring gear 25 for connection with a starting motor. A pair of annular driving members or discs 21 and 25 are carried by a flywheel, the outer disc 21 being rotatable in a single plane and secured to the flywheel by screws 25, while the inner disc 25 constitutes a pressure plate and is shiftable axially toward and from the disc 21. In order accurately to pilot the disc 25, it is provided with a bored central boss 25 having a sliding fit on a pilot sleeve 30 which surrounds the ball bearing l9. At suitably spaced points, the pressure plate 25 is formed on its inner face with lugs 3| of substantial proportions, said lugs fitting slidably into transverse apertures 32 in the web of the flywheel, and constituting keys for imparting rotary movement to the axially shiftable member 25. Normally, the member 25 is urged away from the flywheel and toward the disc 21 by the action of a series of compression springs 33 disposed in sockets 34 in the flywheel, and this spring pressure is made use of to effect a clamping action on an annular driven clutch member, disc, or friction plate 35 which is disposed between the members 21 md 25, and keyed to the driven shaft l2. It is t clamping action that effects a driving connection between the two shafts H and I2, and it is greatly facilitated by linings 31 of friction material on the opposite faces of the driven member 35, such linings being held in place by rivets 35, or otherwise as desired.

The driven clutch element or friction plate 35 has an offset central flange 40 secured by rivets 4| to a disc 42, which in turn has a central hub 43 splined on the shaft |2. This splined connection permits the element 35 to have a slight axial movement, but the extent of such movement is not necessarily very great. Incidentally, it is to be noted that the disc 42 is formed with angularly disposed oil rings 44 to cooperate with similar rings on the member 28 and on the wall 25 of the transmission case to prevent oil from reaching the friction surface.

In order to eflect disengagement of the clutch and thus to break the driving connection between the shafts ii and I2, suitable means are provided within the flywheel and crankshaft. For example, a plurality of levers 45 are radially disposed in grooves 45 in the inner face of the flywheel, said grooves intersecting the transverse apertures 32, and the outer ends of said levers being disposed in radial slots 41 in the key lugs 3|. The number of levers 45 corresponds with the number of lugs 3|, there being three of each in the illustrated embodiment, but of course more than three may be employed if desired. The outer end of each lever 45 is substantially circular, as shown in Fig. 1, whereby to have a free fit in the corresponding lug 3 while the body of each lever,

intermediate its ends, is enlarged in width and adapted to bear against the outer surface of the shaft flange 2|, as well as against the bottom of the groove 45. In other words, each lever is rockable at the points A and B, whence it tapers inwardly to an end of reduced width.

The inner ends of the three levers 45 come practically together at the center of the flywheel, and are there engaged by one end 49 of a plunger or piston 55 which is slidably disposed in a central bore 5| constituting a pressure cylinder in the end of the driving shaft l. A light coil spring 52 normally maintains the pistons against the ends of the levers 45 so that there will be no lost motion in any of the parts, but the strength of said spring 52 is not sufficient to release the clutch. Thus by introducing fluid under pressure to the inner end of the cylinder bore 5|, the piston 50 will be forced outwardly toward the clutch unit, causing the equalizing levers 45 to rock on the points 3 and moving the inner driving disc 28 to its disengaging position against the pressure of the springs 33. When this occurs, the normal clamping pressure on the driven disc 35 is relieved so that the driving connection is broken between the shafts II and I2.

While various ways may be resorted to for introducing the pressure fluid to the cylinder bore 5 I, I find it expedient to do this through the rear main bearing I4 oi the engine. For example, the bearing may have its inner surface formed with an annular groove 55 communicating with a port 51 from a, suitable pipe or fluid supply line, while the crankshaft II is formed with a transverse port 55 registering with the groove 55 and leading into the cylinder bore 5| adjacent the inner end thereof. Preferably, the actuating fluid is oil, fed from a pedal-controlled master cylinder of any desired form, and the system (including said ports, groove, and inner end of cylinder) is normally filled at a minimum pressure. Either ordinary lubricating oil from the engine oiling system, or a special non-freezing fluid may be used, as desired.

The novel clutch, constructed as described above, has many advantages, among which are the following:

(1) The actuating springs and levers, being disposed within the plane of rotation of the flywheel, are completely protected from injury;

(2) Such disposition of these parts gives more perfect balance to the complete assembly and leaves the exterior substantially smooth;

(3) The clutch unit is much shorter than prior art devices, and therefore, effects a saving in space which is important in motor vehicles, particularly where the drive is through the front axle;

(4) This reduction in length is further made possible by arranging the actuating means at the drive shaft end of the unit;

(5) The piston and equalizing levers are so re lated to the crank shaft when fluid pressure is applied to release the clutch that the end thrust on the shaft is equalized or balanced;

(6) Lubrication difliculties are not present. Other advantages will be obvious to those skilled in the art.

The anti-friction pilot bearing I8 may be initially packed with grease or the like, as usual, and various ways may be resorted to for replenishing the lubricant, if desired. By way of example, the driven shaft |2 in the illustrated embodiment has been shown as formed with a longitudinal passage 55 ofiset from the axis of the shaft and extending rearwardly to a point where it meets an inclined radial passage 5|. The forward or outer end of the passage 55 leads into the housing where the bearing i8 is located, while the outer end of the passage 5| is in the gear l5 of the shaft is driven by centrifugal force through passage 60 to the bearing [8.

In Fig. 3, I have diagrammatically illustrated a conventional motor vehicle chassis in order fully to disclose one of the practical uses of the invention. In this view, the chassis frame 95 is'resillently supported on front and rear axles 88 and 91, respectively, said axles having the usual road wheels 58 provided with hydraulic brakes 59. The engine E and transmission case T maybe of any ordinary or preferred type, but instead of being separated by the usual clutch housing, they may be secured directly together, the clutch unit i being disposed with the flywheel 20 in the bell housing of the engine crank case. Under the control of a pedal 10, fluid pressure may be generated to apply the hydraulic brakes 89, and similarly under the control of a pedal Ii, fluid pressure may be generated to release the clutch ill. While various types of master cylinders may be employed for generating the fluid pressure referred to, I may prefer to make use of a novel control unit such as will now be described.

Referring particularly to Figs. 4, 5, and 6, it will be seen that this novel control unit comprises a body portion 13 which is formed with two spaced parallel cylindrical bores '18 and 11, the bore 15 being for the clutch control and the bore 11 being for the brake control. Slidably disposed within the bore 15 is a piston or plunger 18 which is acted upon by a compression spring 19 in the lower end of the cylinder, so that the piston or plunger is normally urged upwardlyto an extreme position limited by an annular shoulder 89. The lower end of the cylinder I6 is fitted with any suitable form of cap 8! having an outlet opening for connection with a. coupling member 82, whereby the interior of the cylinder 16 can be placed in communication with theport 51 in the engine bearing, through the medium of a passage or tube 83.

In its upper side the piston 18 is provided with an extension 84 of reduced diameter and which in the illustrated embodiment is formed of a separate piece of material and connected to the piston 18 by means of a T-shaped end 85, which facilitates assembly and alinement of the parts. This extension 84 normally comes to rest in a position above the top of the body member 15, as is clearly shown in Fig. 5, and is slidably engaged by the rounded end 85 of an actuating lever 81, which is secured in any desired manner to a rock shaft 88. The foot pedal Ii is secured to the outer end of the rock shaft 88 so that movement of said pedal by the operator of the car in which his installed will result in corresponding movements of the lever 81 so as to move the pistons 18 downwardly and upwardly within the cylinder 16. The shaft 88 is, of course, appropriately journaled at 89 in the body portion 15 and preferably is held in place by a removable cap 90 which constitutes a closure for the upper side of the body 15, said cap being clamped in position by screw-threaded elements 9i, or other suitable means. Thus, as the foot pedal H is depressed, the lever 81 is caused to rock in a counter-clockwise direction, as viewed in Fig. 5, with the result that the piston 18 is moved downwardly in the cylinder 15 and againstthe pressure of thespring 19, whereby to put pressure on the oil or other pressure fluid contained within the cylinder and to transmit such fluid pressure through the pipe 83, ports 51 and 58, to the clutch-actuating cylinder and thus release the clutch, as has been previously explained. When the foot pressure is subsequently released from the pedal II, it will, of course, return to its normal position of rest, permitting the piston 18 to move upwardly again in the cylinder under the influence of the spring I9.

It is desirable to cushion the upward movement of the piston 18 Just before it comes to rest in its uppermost position so that the clutch will not be caused to engage too quickly, and for this reason the sidewall of the cylinder 16 is formed with one ormore longitudinal grooves 92 through which some of the pressure fluid can reach the upper side of the piston 18 when the piston hasmoved downwardly in the cylinder a certain extent. The groove, or grooves 92, do not extend entirely up to the limiting shoulder 80 but terminate below the same sufllciently to constitute an annular trap for some of the fluid which thus passes to the upper side of the piston as it operates. In other words, a dashpot effect is produced by this construction so as to retard the upward movement of the piston at the end of its upward stroke, and the fluid which has become trapped at the upper side of the piston is allowed slowly to return to the lower side of the piston through a small port or passage 98 formed diagonally in the piston, as illustrated. The cross-sectional area of the passage 93, is of course, restricted so that the entrapped fluid will not flow through it too rapidly to destroy the cushioning effect.

In order to maintain consistent volume of pressure fluid in the system, means are provided for replenishing any losses which might occur through leakage or the like, and this is done through an inlet port 95 which extends through one of the sidewalls of the cylinder 16 and substantially in line with the lower side of the piston 18 when said piston is in its uppermost position of rest. Of course, as the piston begins to descend in its operating stroke, it completely covers the port 95 and imposes its pressure only upon the desired body of fluid within the cylinder. The inlet port 95 in the illustrated embodiment communicates with an oil reservoir 95 located at one side of the body member 15 and preferably a check valve 91 is employed in con junction with the inlet port 95 so as to preclude the transmission of pressure from the cylinder to the reservoir while port 95 is being closed by piston 18. Of course, the reservoir 95 may be kept supplied withthe oil or other fluid in any desired manner, but I prefer to connect the same through the medium of a pipe 98 or hose to the regular oil circulating system of the automobile engine, whereby the said reservoir will be constantly circulated so that it will be maintained in a clean condition and substantially at a uniform, workable temperature.

Referring more particularly to Fig. 6 of the drawings, it will be seen that the brake control cylinder is constructed somewhat differently from the clutch control cylinder just described and it is primarily characterized by the fact that the braking pressure which is generated and transmitted to the hydraulic brakes 59 of the vehicle is effected through the medium of a special oil or fluid, preferably one which will not be adversely affected by low temperatures, as in winter driving. Such special oil or fluid is disposed within the said cylinder I1 and below the piston I00, which is slidably disposed within the said cylinder, said piston being adapted to come to rest normally in the upper end of the cylinder and against an annular shoulder portion llll of substantial proportions. Above the cylinder I1 and in axial alinement and communication therewith, is another cylindrical bore llI, within which is slidably disposed a plunger Ill which is normally urged upward by a coiled compression spring Ill arranged between the lower side of said plunger and the annular shoulder Ill. Filling the space between the bottom of the plunger Ill and the top of the piston Ill is a body of oil of the same kind as that used in the clutch control cylinder ll and constantly supplied through an inlet port ill from an extension of the reservoir ll. The inlet port I ll is arranged substantially in line with the lower side of the plunger Ill when the latter is in its normal position of rest and so that it will be covered and the supply of oil cut oil by the plunger when the latter commences itsdownward movement.

In order to move the plunger ill downwardly within the cylinder bore III and thus impose pressure on the fluid below it, its upper side is engaged by the rounded end Ill of a lever ll'l very similar to the previously described lever l1, and similarly secured to a rock shaft which is mounted in axial alinement with the rock shaft ll. Secured to the outer end of said shaft Ill is the brake pedal ll.

Thus it will be seen that as the brake pedal ll is depressed by foot power, the lever ill will be caused to rock in a counter-clockwise direction, as viewed in Fig. 6, causing the plunger Ill to move downwardly in the cylinder bore I II against the pressure of the spring ill and thus to generate pressure upon the body of oil confined between the lower side of the plunger Ill and the upper side of the piston Ill. The pressure so generated will, of course, cause the piston Ill, in turn, to move downwardly in its confining cylinder I1 and thus generate pressure upon the body of braking fluid below the piston Ill, such pressure being transmitted through the fluid in the fluid conduits in the usual way to the hydraulic brakes 6! associated with the wheels of the vehicle.

As has been previously stated, any other form of master cylinder may be employed if desired in conjunction with the novel clutch shown in Fig. l of the drawings, or instead of a master cylinder, the clutch may be controlled manually by valves which alternately admit and cut oil the supply of oil or other fluid from a pressure line. In fact, numerous modifications may be resorted to either in the clutch structure or the actuating means, some of such modifications being embodied in the clutch illustrated in Fig. 7.

In this modified embodiment of the invention, the parts have been further simplified in structure and the clutch disposed entirely within the flywheel. Here the driving shaft Ila and the driven shaft iIa are arranged substantially as before described, said shaft Ila being journaled in bearings Ma. One end of the driven shaft lIa is journaled at Ila in the center of the flywheel Ila, which, in turn, is secured to the driving shaft flange Ila by bolts Ila and nuts Ila. The journal at Ila may be provided, as shown, with a bushing of self-lubricating material, or, if desired, an anti-friction bearing may be employed.

The starting motor gear Ila is secured to the flywheel by studs Ila, and is centered by means of an annular shoulder Ilb which closely flts the periphery of the flywheel. The gear Ila is formed with a centrally apertured annular body portion I'la which extends radially inwardly of the rim of the flywheel and of such proportions as to function as the stationary clutch plate. A

movable clutch plate Ila is slida'bly piloted on a central annular support lla formed as an integral part of the flywheel Ila, and said movable clutch plate Ila is formed at suitably spaced points with lugs or projections lla adapted to extend through openings 32a in the web of the flywheel. Furthermore, said disc or plate Ila is provided in one face with sockets for the accommodation of compression springs ll which are concealed within the flywheel and which normally act upon the disc or plate Ila to force the same toward the plate Ila. An intermediate clutch disc lla is disposed between the discs or plates Ill: and Ila, and is provided at its opposite faces with annular lining of friction material 31 whereby to provide for a suitable friction driving engagement between the respective discs. Said intermediate disc lla is securedby rivets or bolts a to a hub member lla which is splined upon the driven shaft lIa whereby to be capable of rotation therewith and relative axial movement.

As in the flrst described embodiment, the axial movement of the disc or plate Ila is controlled by a plurality of equalizing levers "a, the outer ends of which are fltted within suitable openings lla in the lugs I la, while the inner ends of said levers are disposed, as shown adjacent the driving shaft flange Ila. In this embodiment another modification of the invention is illustrated whereby the clutch can be released mechanically rather than hydraulically, and for this purpose the equalizing levers 45a adjacent their inner ends are engaged by slidable pins Ill carried by the flange lla. The other ends of the pins Ill abut against a ring member III which constitutes one of the races of a ball bearing assembly which encircles the main bearing Ila of the engine and which cooperates with an opposing ring or race member III to confine between them a plurality of anti-friction balls or rollers Ill. The ring member III is provided with an annular flange Ill and is normally engaged by the free ends of a yoke or fork II! which straddles the flange Ill and is secured upon a rock shaft Ill through the medium of suitable clamping elements H1 and ill. The rock shaft Ill is connected in any suitable manner, either directly or indirectly, with a foot pedal of conventional form and by means of which the rock shaft may be actuated to control the engagement or disengagement of the clutch. Thus, if the foot pedal is depressed, the rock shaft Ill will be caused to rock in a counterclockwise direction, as viewed in Fig. 7, moving the free ends of the yoke H inwardly toward the flywheel Ila and acting through the rings III and III to correspondingly move the pins ill against the inner ends of the equalizing levers 45a. Such movement is transmitted through the outer ends of equalizing levers so as to withdraw the movable clutch disc Ila to its disengaging position against the pressure of the springs II, and when this is done the frictional engagement of the discs Ila and Ila is broken from the facings 31 of the intermediate disc 36a. In that way the driving connection between the two shafts is disconnected and will remain disconnected until the foot pressure is released from the pedal, whereupon the parts will automatically return to their normal relative position. The arrangement just described is a highly desirable one, not only because of its simplified construction, but more particularly by reason of the fact that it considerably shortens the entire length of an automobile power plant and it confines the clutch within the limits of the flywheel. By being so confined, the parts of the clutch are adequately protected from. injury which is an additional advantage. The reduction in over-all length is further made possible by arranging the actuating means, i. e., the rock shaft 8, the yoke H and cooperating parts on the driving shaft end of the clutch, which is believed to be a novel arrangement. It is to be understood, however, that the specified clutch arrangement illustrated in Fig. 7, is not limited to a mechanical actuation but can indeed be utilized in connection with the hydraulic control disclosed with reference to Fig. 1.

With reference to the hydraulic control means of Fig. 1, it is to be understood that any conventional or desired form of packing or gland may be employed to lead the oil into or through the shaft, in place of the specific port arrangement shown. Furthermore, it is to be noted that wear of the parts is automatically compensated by the pressure fluid so that there is never any slack in the system, and by reason of this importarit fact, the leverage of the pedal can be made greater than in prior art devices; this of course, is a great advantage. While the invention has been illustrated as applied specifically to a clutch, its salient features and principles may be embodied with equal advantages in a braking system, and in fact, numerous other advantages will be apparent to those skilled in the art to which this invention relates.

Obviously, the invention is susceptible of various changes and modifications other than those specifically shown and described, and the right is herein reserved to make such changes as fall within the scope of the appended claims, without departing from the spirit of the invention.

Having thus described my invention, what I claim is:-

1. In combination with an engine shaft, a flywheel, and driven shaft, a clutch to provide a disengageable" driving connection between said shafts, said clutch comprising an axially movable driving disc carried by the flywheel, a driven disc splined to the driven shaft for limited axial movement thereon and adapted to be frictionally engaged by said driving disc, means located within the web of the flywheel for moving the driving disc to engaging and disengaging positions, and manually controlled actuating means associated with the driving shaft.

2. In combination with an engine shaft, a flywheel, and driven shaft, a clutch to provide a disengageable driving connection between said shafts, said clutch comprising inner and outer driving discs carried by the flywheel, the outer disc being rotatable in a single plane and the inner disc being axially shiftable toward and from the outer disc, a driven disc splined 'to the driven shaft for limited axial movement thereon and disposed between the two driving discs for frictional engagement therewith, a plurality of compression springs concealed within the flywheel and acting normally to force the inner driving disc against the driven disc, and thus to clamp it against the outer driving disc, actuating means arranged within the web of the flywheel and operative to move the inner driving disc to disengaging position against the action of said springs, and means at the driving side of the flywheel to control said actuating means.

3. In combination'with an engine shaft, flywheel, and driven shaft, a clutch to provide disengageable driving connection between said shafts, said clutch comprising inner and outer driving discs carried by the flywheel, the outer tional engagement therewith, said driven shaft being piloted in the center of the flywheel, and actuating means for shifting the inner driving disc into and out of engaging position, said actuating means being disposed in part within the web of the flywheel and in part at the driving shaft side thereof.

4. A clutch comprising annular driving and driven members adapted for relative frictional engagement, one of said members being movable axially into and out of engaging position, yielding means acting normally to maintain said members in engagement with each other, a plurality of radially disposed equalizing levers disposed within the plane of the web of the flywheel and operative to effect said axial movement of one of the members to disengaging position against the action of said yielding means, and fluidpressure means for actuating said levers simultaneously.

5. A clutch comprising annular driving and driven members adapted for relative frictional engagement, one of said members being movable axially into and out of engaging position, yielding means acting to engage or disengage said members relative to each other, a plurality of radially disposed equalizing levers located in the web of the flywheel and operative to effect said axial movement of one of the members to disengaging position and against the action of said yielding means, and centrally disposed fluid pressure means operative against the inner ends of said levers to actuate the same to control disengaging and engaging of the clutch members.

6. In combination with driving and driven shafts a clutch providing a disengageable driving connection between the shafts, said clutch comprising driving and driven discs associated with the respective shafts, yielding means acting normally to maintain said discs in engagement with each other, and fluid-pressure means centrally disposed in the driving shaft to move one of the discs axially away from the other to effect disengagement of the clutch.

7. In combination with driving and driven shafts, a clutch providing a disengageable driving connection between the shafts, said clutch comprising driving and driven discs associated with the respective shafts, yielding means acting normally to maintain said discs in engagement with each other, a plurality of radially disposed equalizing levers operative to effect axial movement of the driving disc away from the driven shaft and against the action of said yielding means, a pressure-responsive piston slidable in a central cylindrical bore in the driving shaft, said piston being operable against the inner end of said equalizing levers to actuate the same, the parts being so arranged as to function in releasing the clutch without imposing any end thrust on the driving or driven shafts, and means to supply pressure-fluid to the inner side of the piston in said bore.

8. In combination with driving and driven shafts, a clutch for providing a driving coimection between said shafts, said clutch comprising friction members associated respectively with the 7g shafts, means for normally maintaining the friction members in engagement with each other, fluid-pressure means in the end of the driving shaft for effecting disengagement of the friction members without imposing any substantial endthrust on the shaft, and means for supplying pressure-fluid to said means through one of the shafts.

9. In combination with an engine shaft, flywheel, and driven shaft, a clutch to provide a disengageable driving connection between .said shafts, said clutch comprising an axially movable driving disc carried by the flywheel, a driven disc slidabLv keyed to the driven shaft and adapted to be frictionally engaged by said driving disc, a plurality of compression springs concealed within the flywheel and acting normally to maintain the driving disc against the driven disc, a plurality of radial equalizing levers disposed in grooves in the flywheel and constituting pry connections for disengaging the discs against the action of said springs, a piston slidable in a central cylindrical bore in the end of the driving shaft, said piston being operative against the inner ends of said levers to disengage the clutch discs, and means for supplying pressure-fluid to the inner side of the piston through the driving shaft.

10. In combination with an engine shaft, flywheel, and driven shaft, a clutch to provide a disengageable driving connection between said shafts, said clutch comprising inner and outer driving discs carried by the flywheel, the outer disc being rotatable in a single plane and the inner disc being axially shiftable toward and from the outer disc, a driven disc splined to the driven shaft and disposed between the two drivin discs for frictional engagement therewith, means disposed within theflywheel for shifting said inner driving disc, and fluid-pressure means associated with the driving shaft and adapted to control said disc shifting means.

11. In combination with an engine shaft, flywheel, and driven shaft, a clutch to provide a disengageable driving connection between said shafts, said clutch comprising an axially movable driving disc carried by the flywheel, a driven disc keyed to the driven shaft for limited axial movement thereon and adapted to be frictionally engaged by said driving disc, a plurality of compression springs concealed within sockets in the flywheel and acting normally to maintain the driving disc against the driven disc, a plurality of radial equalizing levers disposed without fas- .tenlng means in grooves in the flywheel and constituting pry connections for disengaging the discs against the action of said springs, an axially shiftable annulus encircling the driving shaft and operatively connected with the inner ends of said levers, and means for shifting said annulus to release the clutch.

12. In combination with a driving shaft and a driven shaft a wheel member carried by the driving shaft and formed with a plurality" of radial grooves in one of its faces and a correspondin number of transverse apertures adjacent the outer ends of said grooves, a circular guide flange on the opposite face of the wheel member, an outer driving friction disc carried by the wheel member and rotatable in a single plane, an inner driving friction disc centrally supported by the said guide flange on the wheel member and movable axially with reference thereto, said inner driving friction disc being provided with lugs which extend inwardly through the transverse apertures in the wheel member, a driven friction disc splined to the driven shaft and between the two driving discs for frictional engagement therewith, aplurality of equalizing levers rockably disposed in the radial grooves of the wheel member and having their outer ends loosely connected with the lugs of the inner driving disc, and means operative against the inner ends of said levers for rocking the same to move the inner driving disc axially to engaging and disengaging positions. v

13. In combination with an engine shaft and a driven shaft, a flywheel carried by the engine shaft and formed with a plurality of radial grooves in one of its faces and a corresponding number of transverse apertures adjacent the outer ends of said grooves, a circular guide flange integrally formed on the opposite face of the flywheel, an outer driving clutch disc carried by the flywheel and rotatable in a single plane, an inner driving clutch disc centrally supported by the said guide flange on the flywheel and movable axially with reference thereto, said inner driving clutch disc being provided with lugs which extend inwardly through the transverse apertures in the flywheel, a driven clutch disc splined to the driven shaft and disposed between the two driving discs for. frictional engagement therewith, resilient means within the flywheel and acting normally'to force said inner disc against said driven disc and thus to clamp it against said outer driving disc, a plurality of equalizing levers rockably disposed in the radial grooves of the flywheel and having their outer ends loosely connected with the lugs of the inner driving disc, and means operative against the inner ends of said-levers for rocking the same to move the inner driving disc to disengaging position against the action of said resilient means.

I 14. In combination with an engine shaft and a driven shaft, a flywheel carried by the engine shaft and formed with a plurality of radial grooves in one of its faces and a corresponding number of transverse apertures adjacent the outer ends of said grooves, a circular guide flange integrally formed on the opposite face of the flywheel, an outer driving clutch disc carried by the flywheel and rotatable in a single plane, an inner driving clutch disc centrally supported by the said guide flange on the flywheel and movable axially with reference thereto, said inner driving clutch disc being provided with integral lugs which extend inwardly through the transverse apertures in the flywheel, a driven clutch disc splined to the driven shaft and disposed between the two driving discs for frictional engagement therewith, a plurality of compressin springs concealed within the flywheel and acting normally to force said inner disc against said driven disc and thus to clamp it against said outer driving disc, a plurality of equalizing levers rockably disposed in the radial grooves of the flywheel and having their outer ends loosely connected with the lugs of the inner driving disc, and means associated with the engine shaft and operative against the inner ends of said levers for rocking the same to move the inner driving disc to disengaging position against the action of said compression springs.

15. In combination with an engine shaft and a driven shaft, a flywheel carried by the engine shaft and formed with a plurality of radial grooves in one of its faces and a corresponding number of transverse apertures adjacent the outer ends of said grooves, a circular guide flange integrally formed on the opposite face of the flywheel, an outer driving clutch disc carried by mally to force said inner disc against said driven disc and thus to clamp it against said outer driving disc, a plurality of equalizing levers rockably disposed in the radial grooves of the flywheel and having their outer ends loosely connected with the lugs of the inner driving disc, means responsive to fluid pressure for actuating the levers by engaging the inner ends thereof, and means for leading the pressure fluid to said actuating means through the engine shaft.

16. In combination with an engine shaft and a driven-shaft a flywheel carried by the engine shaft and formed with a plurality of radial grooves in one of its faces and a corresponding number of transverse apertures adjacent the outer ends of said grooves, a circular guide flange integrally formed on the opposite face of the flywheel, an outer driving clutch disc carried by the flywheel and rotatable in a single plane, an inner driving clutch disc centrally supported by the said guide flange on the flywheel and movable axially with reference thereto, said inner driving clutch disc being provided with integral lugs which extend inwardly through the transverse apertures in the flywheel, a driven clutch disc splined to the driven shaft and disposed between the two driving discs for frictional engagement therewith, a plurality of compression springs concealed within the flywheel and acting normally to force said inner disc against said driven disc and thus to clamp it against said outer driving disc, a plurality of equalizing levers rockably disposed in the radial grooves of the flywheel and having their outer ends loosely connected with the lugs of the inner driving disc, and means for mechanically actuating said levers, said means including slidable elements which are rotatable with the engine shaft and which engage the inner ends of said levers.

17. In combination with a driving shaft and a driven shaft, a wheel member carried by the driving shaft and formed with a plurality of radial grooves in one of its faces and a corresponding number of transverse apertures adjacent the outer ends of said grooves, a circular guide flange on the opposite face of the wheel member, an outer driving friction disc carried by the wheel member and rotatable in a single plane, an inner driving friction disc centrally supported by the said guide flange on the wheel member and movable axially with reference thereto, said inner driving friction disc being provided with lugs which extend inwardly through the transverse apertures in the wheel member, a driven friction disc splined to the driven shaft and disposed between the two driving discs for frictional engagement therewith, a plurality of equalizing .=levers rockably disposed in the radial grooves of the wheel member and havingtheir outer ends loosely connected with the lugs of the inner driving disc, means responsive to fluid pressure for actuating the levers by engaging the inner ends thereof, and means for leading the pressure fluid to said actuating means through the driving shaft.

18. A clutch comprising a driving member having a central bearing portion surrounded by a housing, a driven member piloted in said bearing portion, and means including a pressure plate for establishing a detachable driving connection between the driving and driven members, said pressure plate being centralized and piloted by the outside of the housing which surrounds said bearing.

19. In combination th driving and driven shafts, a clutch providin a disengageable driving connection between th shafts, said clutch comprising driving and dri en members associated with the respective shafts, yielding means acting. normally to maintain said clutch members in engagement with each other, a plurality of radially disposed equalizing members operative to efiect axial movement of the driving clutch member away fromthe driven shaft and against the action of said yielding means, a pressure responsive piston slidable in a central cylindrical bore in the driving shaft, said piston being operable against the inner end of said equalizing members to actuate the same, the parts being so arranged as to function in re leasing the clutch without imposing any end thrust on the driving or driven shafts, and

means to supply pressure fluid to the, inner' said bore. 

